In motor vehicles equipped with electronically controlled engine fueling systems, vehicle operating parameters such as engine output power and vehicle road speed are typically controlled in accordance with engine fueling control algorithms. Such algorithms regulate engine output and road speed based on requested torque and other factors, wherein requested torque may be computer generated, such as in accordance with the operation of known motor vehicle cruise control systems, or may be manually generated via driver actuation of an accelerator pedal. The terms "torque request", "requested torque" and "torque request signal" as used hereinafter are defined as encompassing either "commanded throttle position", as this term is commonly understood in the spark ignited engine industry, or "commanded fueling rate", as this term is commonly understood in the compression ignition engine industry.
In many motor vehicle applications, particularly in the medium and heavy duty vehicle industries, vehicle and/or engine acceleration rates are important factors in determining engine fueling requirements. Such engine fueling requirements are therefore typically designed to ensure at least minimum vehicle acceleration rates under the most adverse conditions such as, for example, when over-the-road heavy duty trucks or industrial vehicles are hauling full cargo loads up steep inclines.
Designing engine fueling requirements in this manner, however, has drawbacks associated therewith. For example, designing engine fueling requirements to ensure minimum vehicle acceleration rates under adverse conditions also ensures that increasingly higher vehicle acceleration rates become available as the adverse conditions lessen in severity. At some point, available vehicle acceleration rates become excessive and begin to compromise fuel economy as well as engine/vehicle component integrity. It is well known in the motor vehicle industry that operating a vehicle with excessive vehicle acceleration can drastically reduce fuel economy in the short term, and decrease useful lifetimes of various vehicle and engine components in the long term.
What is therefore needed is a system for managing and controlling vehicle and/or engine acceleration rates. Such a system should ideally ensure adequate vehicle acceleration under adverse operating conditions while limiting vehicle and/or engine acceleration before such acceleration becomes excessive.